This invention concerns a method to detect man-made fibers and/or defective fibers and/or other foreign materials in the processing of silk waste, and the relative apparatus.
To be more exact, the invention concerns a method and the relative apparatus to identify man-made fibers, advantageously but not only polypropylene fibers, defective fibers and/or other foreign materials included in laps of silk fibers coming from the processing of silk waste.
Moreover, the method and the relative apparatus according to the invention enable the faults detected in the lap of silk fibers to be classified and counted and to be sorted by types.
This method and the relative apparatus are applied advantageously to the textile industry, for instance downstream of a drawing frame, and in particular to the quality control step, whether that step is performed by sampling or not.
This control of quality can be carried out either by a classification of the laps of silk fibers on the basis of the man-made fibers and/or the defective fibers and/or other foreign materials encountered or by combining the control with successive apparatuses so as to eliminate such faults and/or such man-made or defective fibers thus identified.
It is known that during recent years the old packages based on cellulose in which silk wastes were conveyed from their collection points to their recovery and re-use points have been replaced by packages containing man-made fibers particularly polypropylene fibers.
The technology of the state of the art had already obtained a system to identify cellulose fibers in laps of silk fibers.
The technology of the state of the art has made possible the identification, on a lap of silk fibers leaving a drawing frame or like machine, of some types of faults by using the field of the data processing of images.
The present technique of the data processing of images is carried out substantially in three different successive steps, and in particular by the acquiring of the image, the data processing of the image and the actual identification of a determined type of foreign or defective fibers or materials.
According to the known methods the lap of silk fibers is fed forwards at a set speed and is scanned by a telecamera connected to a computer into which is loaded a program that converts the visual image into data compatible for analysis.
Special algorithms make possible the identification of a series of faults present in the image taken by the telecamera, and the classification of the lap of silk fibers takes place on the basis of the faults detected.
But the technology of the state of the art is powerless in the case of man-made fibers and, in particular, polypropylene fibers. This situation therefore entails the shortcoming that these polypropylene fibers contaminate the silk fibers and impair the quality.
With the state of the art the various laps of silk fibers are classified automatically on the basis of the quantity and type of the faults.
This classification does not include the contamination by man-made fibers present in the lap of silk fibers since these man-made fibers are sometimes identified as being "not silk" but are not identified as being man-made fibers.
Such an improvement of the classification is still impossible as no method and therefore no apparatus exist for the identification of the man-made fibers present in laps of silk fibers.
At the present time the samples of laps of silk fibers are inspected visually by the appointed personnel, who try to detect any man-made fibers and, in particular, polypropylene in the lap of silk.
As this operation requires great care and concentration on the part of the machine operator, the present speed of inspection is about 0.4 to 0.5 meters of the lap of silk fibers per minute, and the outcome of this situation is that the classification of the laps of silk fibers is made on the basis of an inspection carried out on very small samples and that therefore the statistical results are sometimes not very reliable.
U.S. patent Application 4,839,943 discloses a device to detect faults such as natural or man-made foreign fibers, knotted strings, bunches of synthetic materials, pieces of thread within or between tufts of particular loose textile fibers such as cotton, wool, etc.
The foreign fibers are detected on the basis of their various characteristics, such as configuration and/or color and/or size and/or luminosity, but this method does not enable the faults to be detected by their type and limits itself only to the identification of everything which does not correspond to the fiber being processed at the time.
The device to detect faults comprises advantageously a means to transmit electromagnetic waves to a means which receives those waves, the two means being arranged opposite to each other on one side and the other side of the layer of fibers to be analysed.
The device to detect faults is of a camera or telecamera type and the images thus produced are stored and compared, by means of a suitable evaluation contrivance, with photographs stored in the device so as to identify as faults everything not consisting of the particular required fiber.
The detector device actuates a suitable removal means positioned downstream to remove the faults previously identified.
Furthermore, this device cannot count nor classify the various faults as being what they are but makes a rough evaluation of the fibers and identifies everything which is considered as material foreign to the actual fiber being examined.
The device is applied, in fact, to fibers which are not scoured nor beaten but are merely opened and spread on a conveyor belt; the fibers contain great quantities of impurities such as seeds, vegetable fragments, dusts, etc., and these impurities are included even in quantities consisting of some percentage by weight of the mass being processed.
WO-91/11705 discloses a method to measure optically the characteristics of quality and quantity of textile fibers. The method enables, in particular, the length, fineness, degree of maturity and curliness of the fibers, whichever they are, to be established at the same time.
The method is applied to a single-layer sample of fibers consisting of a limited number of fibers made parallel and positioned between two glasses but cannot be applied to laps of continuous fibers for an in-line analysis and inspection process. Moreover, this method does not lead to identification of faults in the sample of fibers analysed and therefore does not enable the sample under examination to be classified on the basis of the type and number of faults identified.